Optimization of Screening Media to Improve Antimicrobial Biodiscovery from Soils in Undergraduate/Citizen Science Research-Engaged Initiatives

<b>Background/Objectives:</b> Research-engaged academic institutions offer the opportunity to couple undergraduate education/citizen science projects with antimicrobial biodiscovery research. Several initiatives reflecting this ethos have been reported internationally (e.g., Small World,...

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Main Authors: Leah McPhillips, John O’Callaghan, Carmel Shortiss, Stephen A. Jackson, Niall D. O’Leary
Format: Article
Language:English
Published: MDPI AG 2024-10-01
Series:Antibiotics
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Online Access:https://www.mdpi.com/2079-6382/13/10/956
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author Leah McPhillips
John O’Callaghan
Carmel Shortiss
Stephen A. Jackson
Niall D. O’Leary
author_facet Leah McPhillips
John O’Callaghan
Carmel Shortiss
Stephen A. Jackson
Niall D. O’Leary
author_sort Leah McPhillips
collection DOAJ
description <b>Background/Objectives:</b> Research-engaged academic institutions offer the opportunity to couple undergraduate education/citizen science projects with antimicrobial biodiscovery research. Several initiatives reflecting this ethos have been reported internationally (e.g., Small World, Tiny Earth, MicroMundo, Antibiotics Unearthed). These programs target soil habitats due to their high microbial diversity and promote initial screening with non-selective, nutrient media such as tryptic soy agar (TSA). However, evaluation of published outputs to date indicates that isolate recovery on TSA is consistently dominated by the genera <i>Bacillus</i>, <i>Pseudomonas,</i> and <i>Paenibacillus</i>. In this study, we evaluated the potential of soil extract agar to enhance soil isolate diversity and antibiosis induction outcomes in our undergraduate Antibiotics Unearthed research program. <b>Methods:</b> We comparatively screened 229 isolates from woodland and garden soil samples on both tryptic soy agar (TSA) and soil extract agar (SEA) for antimicrobial activity against a panel of clinically relevant microbial pathogens. <b>Results:</b> On one or both media, 15 isolates were found to produce zones of clearing against respective pathogens. 16S rRNA gene sequencing linked the isolates with three genera: <i>Streptomyces</i> (7), <i>Paenibacillus</i> (6), and <i>Pseudomonas</i> (2). Six of the <i>Streptomyces</i> isolates and one <i>Pseudomonas</i> demonstrated antimicrobial activity when screened on SEA, with no activity on TSA. Furthermore, incorporation of the known secondary metabolite inducer N acetyl-glucosamine (20 mM) into SEA media altered the pathogen inhibition profiles of 14 isolates and resulted in broad-spectrum activity of one <i>Streptomyces</i> isolate, not observed on SEA alone. In conclusion, SEA was found to expand the diversity of culturable isolates from soil and specifically enhanced the recovery of members of the genus <i>Streptomyces</i>. SEA was also found to be a superior media for antibiosis induction among <i>Streptomyces</i> isolates when compared to TSA. It was noted that <i>Paenibacillus</i> isolates’ antibiosis induction demonstrated a strain-specific response with respect to the growth media used. <b>Conclusions:</b> The authors propose SEA inclusion of in soil screening protocols as a cost-effective, complementary strategy to greatly enhance outcomes in undergraduate/citizen science-engaged antimicrobial biodiscovery initiatives.
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spelling doaj-art-384ab8db98c54190acdc1ff37fe3e4402025-08-20T02:11:04ZengMDPI AGAntibiotics2079-63822024-10-01131095610.3390/antibiotics13100956Optimization of Screening Media to Improve Antimicrobial Biodiscovery from Soils in Undergraduate/Citizen Science Research-Engaged InitiativesLeah McPhillips0John O’Callaghan1Carmel Shortiss2Stephen A. Jackson3Niall D. O’Leary4John Innes Centre, Norwich NR4 7UH, UKSchool of Microbiology, University College Cork, T12 K8AF Cork, IrelandSchool of Microbiology, University College Cork, T12 K8AF Cork, IrelandSchool of Microbiology, University College Cork, T12 K8AF Cork, IrelandSchool of Microbiology, University College Cork, T12 K8AF Cork, Ireland<b>Background/Objectives:</b> Research-engaged academic institutions offer the opportunity to couple undergraduate education/citizen science projects with antimicrobial biodiscovery research. Several initiatives reflecting this ethos have been reported internationally (e.g., Small World, Tiny Earth, MicroMundo, Antibiotics Unearthed). These programs target soil habitats due to their high microbial diversity and promote initial screening with non-selective, nutrient media such as tryptic soy agar (TSA). However, evaluation of published outputs to date indicates that isolate recovery on TSA is consistently dominated by the genera <i>Bacillus</i>, <i>Pseudomonas,</i> and <i>Paenibacillus</i>. In this study, we evaluated the potential of soil extract agar to enhance soil isolate diversity and antibiosis induction outcomes in our undergraduate Antibiotics Unearthed research program. <b>Methods:</b> We comparatively screened 229 isolates from woodland and garden soil samples on both tryptic soy agar (TSA) and soil extract agar (SEA) for antimicrobial activity against a panel of clinically relevant microbial pathogens. <b>Results:</b> On one or both media, 15 isolates were found to produce zones of clearing against respective pathogens. 16S rRNA gene sequencing linked the isolates with three genera: <i>Streptomyces</i> (7), <i>Paenibacillus</i> (6), and <i>Pseudomonas</i> (2). Six of the <i>Streptomyces</i> isolates and one <i>Pseudomonas</i> demonstrated antimicrobial activity when screened on SEA, with no activity on TSA. Furthermore, incorporation of the known secondary metabolite inducer N acetyl-glucosamine (20 mM) into SEA media altered the pathogen inhibition profiles of 14 isolates and resulted in broad-spectrum activity of one <i>Streptomyces</i> isolate, not observed on SEA alone. In conclusion, SEA was found to expand the diversity of culturable isolates from soil and specifically enhanced the recovery of members of the genus <i>Streptomyces</i>. SEA was also found to be a superior media for antibiosis induction among <i>Streptomyces</i> isolates when compared to TSA. It was noted that <i>Paenibacillus</i> isolates’ antibiosis induction demonstrated a strain-specific response with respect to the growth media used. <b>Conclusions:</b> The authors propose SEA inclusion of in soil screening protocols as a cost-effective, complementary strategy to greatly enhance outcomes in undergraduate/citizen science-engaged antimicrobial biodiscovery initiatives.https://www.mdpi.com/2079-6382/13/10/956biodiscoveryantimicrobial resistancescreening mediasoil extract agarN-acetyl glucosamineactinobacteria
spellingShingle Leah McPhillips
John O’Callaghan
Carmel Shortiss
Stephen A. Jackson
Niall D. O’Leary
Optimization of Screening Media to Improve Antimicrobial Biodiscovery from Soils in Undergraduate/Citizen Science Research-Engaged Initiatives
Antibiotics
biodiscovery
antimicrobial resistance
screening media
soil extract agar
N-acetyl glucosamine
actinobacteria
title Optimization of Screening Media to Improve Antimicrobial Biodiscovery from Soils in Undergraduate/Citizen Science Research-Engaged Initiatives
title_full Optimization of Screening Media to Improve Antimicrobial Biodiscovery from Soils in Undergraduate/Citizen Science Research-Engaged Initiatives
title_fullStr Optimization of Screening Media to Improve Antimicrobial Biodiscovery from Soils in Undergraduate/Citizen Science Research-Engaged Initiatives
title_full_unstemmed Optimization of Screening Media to Improve Antimicrobial Biodiscovery from Soils in Undergraduate/Citizen Science Research-Engaged Initiatives
title_short Optimization of Screening Media to Improve Antimicrobial Biodiscovery from Soils in Undergraduate/Citizen Science Research-Engaged Initiatives
title_sort optimization of screening media to improve antimicrobial biodiscovery from soils in undergraduate citizen science research engaged initiatives
topic biodiscovery
antimicrobial resistance
screening media
soil extract agar
N-acetyl glucosamine
actinobacteria
url https://www.mdpi.com/2079-6382/13/10/956
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